scholarly journals A robust measure of event isotropy at colliders

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Cari Cesarotti ◽  
Jesse Thaler
Keyword(s):  
Phase Space ◽  
Uniform Distribution ◽  
Radiation Pattern ◽  
Dynamic Range ◽  
New Physics ◽  
Event Shape ◽  
Proton Proton ◽  
Strongly Coupled ◽  
Electron Positron ◽  
Minimum Work

Abstract We introduce a new event shape observable — event isotropy — that quantifies how close the radiation pattern of a collider event is to a uniform distribution. This observable is based on a normalized version of the energy mover’s distance, which is the minimum “work” needed to rearrange one radiation pattern into another of equal energy. We investigate the utility of event isotropy both at electron-positron colliders, where events are compared to a perfectly spherical radiation pattern, as well as at proton-proton colliders, where the natural comparison is to either cylindrical or ring-like patterns. Compared to traditional event shape observables like sphericity and thrust, event isotropy exhibits a larger dynamic range for high-multiplicity events. This enables event isotropy to not only distinguish between dijet and multijet processes but also separate uniform N-body phase space configurations for different values of N. As a key application of this new observable, we study its performance to characterize strongly-coupled new physics scenarios with isotropic collider signatures.

scholarly journals The present and future of four top operators

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Giovanni Banelli ◽  
Ennio Salvioni ◽  
Javi Serra ◽  
Tobias Theil ◽  
Andreas Weiler
Keyword(s):  
Top Quark ◽  
High Energy ◽  
New Physics ◽  
Effective Field ◽  
Proton Proton ◽  
Strongly Coupled ◽  
Composite Higgs ◽  
Electron Positron ◽  
Energy Frontier ◽  
The Impact

Abstract We study the phenomenology of a strongly-interacting top quark at future hadron and lepton colliders, showing that the characteristic four-top contact operators give rise to the most significant effects. We demonstrate the extraordinary potential of a 100 TeV proton-proton collider to directly test such non-standard interactions in four-top production, a process that we thoroughly analyze in the same-sign dilepton and trilepton channels, and explore in the fully hadronic channel. Furthermore, high-energy electron-positron colliders, such as CLIC or the ILC, are shown to exhibit an indirect yet remarkable sensitivity to four-top operators, since these constitute, via renormalization group evolution, the leading new-physics deformations in top-quark pair production. We investigate the impact of our results on the parameter space of composite Higgs models with a strongly-coupled (right-handed) top quark, finding that four-top probes provide the best sensitivity on the compositeness scale at the future energy frontier. In addition, we investigate mild yet persisting LHC excesses in multilepton plus jets final states, showing that they can be consistently described in the effective field theory of such a new-physics scenario.

scholarly journals Future Circular Colliders

2019 ◽  
Vol 69 (1) ◽  
pp. 389-415 ◽  
Author(s):  
M. Benedikt ◽  
A. Blondel ◽  
P. Janot ◽  
M. Klein ◽  
M. Mangano ◽  
...  
Keyword(s):  
Particle Physics ◽  
Hadron Collider ◽  
Center Of Mass ◽  
Heavy Ion ◽  
New Physics ◽  
Proton Proton ◽  
Proton Collisions ◽  
Center Of Mass Energy ◽  
Physics Program ◽  
Electron Positron

After 10 years of physics at the Large Hadron Collider (LHC), the particle physics landscape has greatly evolved. Today, a staged Future Circular Collider (FCC), consisting of a luminosity-frontier highest-energy electron–positron collider (FCC-ee) followed by an energy-frontier hadron collider (FCC-hh), promises the most far-reaching physics program for the post-LHC era. FCC-ee will be a precision instrument used to study the Z, W, Higgs, and top particles, and will offer unprecedented sensitivity to signs of new physics. Most of the FCC-ee infrastructure could be reused for FCC-hh, which will provide proton–proton collisions at a center-of-mass energy of 100 TeV and could directly produce new particles with masses of up to several tens of TeV. This collider will also measure the Higgs self-coupling and explore the dynamics of electroweak symmetry breaking. Thermal dark matter candidates will be either discovered or conclusively ruled out by FCC-hh. Heavy-ion and electron–proton collisions (FCC-eh) will further contribute to the breadth of the overall FCC program. The integrated FCC infrastructure will serve the particle physics community through the end of the twenty-first century. This review combines key contents from the first three volumes of the FCC Conceptual Design Report.

scholarly journals Highly boosted Higgs bosons and unitarity in vector-boson fusion at future hadron colliders

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Wolfgang Kilian ◽  
Sichun Sun ◽  
Qi-Shu Yan ◽  
Xiaoran Zhao ◽  
Zhijie Zhao
Keyword(s):  
Pair Production ◽  
Vector Boson ◽  
New Physics ◽  
Higgs Bosons ◽  
Vector Boson Fusion ◽  
Final State ◽  
Proton Proton ◽  
Effective Lagrangian ◽  
Discovery Potential ◽  
New Interactions

Abstract We study the observability of new interactions which modify Higgs-pair production via vector-boson fusion processes at the LHC and at future proton-proton colliders. In an effective-Lagrangian approach, we explore in particular the effect of the operator $$ {h}^2{W}_{\mu \nu}^a{W}^{a,\mu \nu} $$ h 2 W μν a W a , μν , which describes the interaction of the Higgs boson with transverse vector-boson polarization modes. By tagging highly boosted Higgs bosons in the final state, we determine projected bounds for the coefficient of this operator at the LHC and at a future 27 TeV or 100 TeV collider. Taking into account unitarity constraints, we estimate the new-physics discovery potential of Higgs pair production in this channel.

scholarly journals Forward backward multiplicity correlations: a tool to study properties of the proton-proton collisions

2018 ◽  
Vol 172 ◽  
pp. 05008 ◽  
Author(s):  
Edgar Dominguez-Rosas ◽  
Eleazar Cuautle Flores
Keyword(s):  
Experimental Data ◽  
Hadron Production ◽  
Event Generator ◽  
Proton Proton ◽  
Proton Collisions ◽  
Electron Positron ◽  
Color Reconnection ◽  
Proton Proton Collisions ◽  
Production Mechanisms ◽  
Reconnection Model

Forward-backward multiplicity correlations have been used to study hadron production mechanisms in electron-positron, proton-proton and more recently in leadlead collisions. The experimental results on this correlations and its comparison to different models reveals an incomplete agreement. In this work, we present an study of forward backward multiplicity correlations in proton-proton collisions using PYTHIA event generator, at LHC energies. Detailed analysis is presented in the case of soft and hard QCD processes, incorporating color reconnection model as part of hadronization mechanism and multiple parton interactions effects in the correlations. Our results and its comparison to available experimental data suggest that this kind of correlations are great tools to characterize the events and gives the possibility to disentangle phenomena in hard and soft QCD processes.

scholarly journals On the Interpretation of Nonresonant Phenomena at Colliders

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Miguel G. Folgado ◽  
Veronica Sanz
Keyword(s):  
New Physics ◽  
Derivative Expansion ◽  
Strongly Coupled ◽  
Null Results ◽  
Goldstone Bosons ◽  
Physics Potential ◽  
Low Energies ◽  
Light Particles ◽  
Integrated Luminosity

With null results in resonance searches at the LHC, the physics potential focus is now shifting towards the interpretation of nonresonant phenomena. An example of such shift is the increased popularity of the EFT programme. We can embark on such programme owing to the good integrated luminosity and an excellent understanding of the detectors, which will allow these searches to become more intense as the LHC continues. In this paper, we provide a framework to perform this interpretation in terms of a diverse set of scenarios, including (1) generic heavy new physics described at low energies in terms of a derivative expansion, such as in the EFT approach; (2) very light particles with derivative couplings, such as axions or other light pseudo-Goldstone bosons; and (3) the effect of a quasicontinuum of resonances, which can come from a number of strongly coupled theories, extradimensional models, clockwork set-ups, and their deconstructed cousins. These scenarios are not equivalent despite all nonresonance, although the matching among some of them is possible, and we provide it in this paper.

scholarly journals Review of strongly-coupled composite dark matter models and lattice simulations

2016 ◽  
Vol 31 (22) ◽  
pp. 1643004 ◽  
Author(s):  
Graham D. Kribs ◽  
Ethan T. Neil
Keyword(s):  
Dark Matter ◽  
Gauge Theory ◽  
Direct Detection ◽  
Bound State ◽  
New Physics ◽  
Abelian Gauge ◽  
Strongly Coupled ◽  
Abelian Gauge Theory ◽  
Lattice Calculations ◽  
Composite Description

We review models of new physics in which dark matter arises as a composite bound state from a confining strongly-coupled non-Abelian gauge theory. We discuss several qualitatively distinct classes of composite candidates, including dark mesons, dark baryons, and dark glueballs. We highlight some of the promising strategies for direct detection, especially through dark moments, using the symmetries and properties of the composite description to identify the operators that dominate the interactions of dark matter with matter, as well as dark matter self-interactions. We briefly discuss the implications of these theories at colliders, especially the (potentially novel) phenomenology of dark mesons in various regimes of the models. Throughout the review, we highlight the use of lattice calculations in the study of these strongly-coupled theories, to obtain precise quantitative predictions and new insights into the dynamics.

scholarly journals Future e+e−Colliders at the Energy Frontier

2019 ◽  
Vol 206 ◽  
pp. 08001
Author(s):  
Tadeusz Lesiak
Keyword(s):  
Higgs Boson ◽  
Particle Physics ◽  
New Physics ◽  
Stages Of Development ◽  
Physics Program ◽  
Electron Positron ◽  
Energy Frontier

A future giant electron-positron collider, operating at the energy frontier, is a natural proposal in order to push particle physics into new regime of precise measurements, in particular in the sectors of electroweak observables and Higgs boson parameters. The four projects of such accelerators: two linear (ILC and CLIC) and two circular (FCC and CEPC) are currently in various stages of development. In view of the update of European HEP strategy for particle physics and expectations of important decisions from Japan, China and USA, the next few years will be critical as far as the decisions about the construction of such colliders are concerned. The paper concisely reviews the relevant aspects and challenges of the proposed accelerators and detectors along with the presumed schedules of construction and operation. The motivation and very attractive physics program for new e+e− colliders, spanning in particular perspectives in Higgs, electroweak, and neutrino sectors, together with expectations of searches for New Physics, will be discussed as well.

scholarly journals QED RADIATIVE CORRECTIONS TO THE DECAY π0→e+e−

1993 ◽  
Vol 08 (18) ◽  
pp. 1691-1700 ◽  
Author(s):  
GEORGE TRIANTAPHYLLOU
Keyword(s):  
Perturbation Theory ◽  
Decay Rate ◽  
Invariant Mass ◽  
New Physics ◽  
Radiative Corrections ◽  
First Order ◽  
Recent Interest ◽  
Electron Positron ◽  
Electron Positron Pair ◽  
First Order Perturbation

In view of the recent interest in the decays of mesons into a pair of light leptons, a computation of the QED radiative corrections to the decay of π0 into an electron-positron pair is presented here. The analysis is based on the soft-photon resummation method, which, unlike first-order perturbation theory, allows for very strict invariant-mass cuts on the final electrons. When combined with the theoretical estimates for the non-radiatively corrected decay rate, the results of the present paper could help to determine if new physics affect this decay.

Piecewise isometries, uniform distribution and 3log 2−π2/8

2011 ◽  
Vol 32 (6) ◽  
pp. 1862-1888 ◽  
Author(s):  
YITWAH CHEUNG ◽  
AREK GOETZ ◽  
ANTHONY QUAS
Keyword(s):  
Phase Space ◽  
Uniform Distribution ◽  
Periodic Orbits ◽  
Periodic Points ◽  
Full Measure ◽  
Infinite Measure ◽  
Important Family ◽  
Large Numbers ◽  
Piecewise Isometries ◽  
Measure Preserving Transformations

AbstractWe use analytic tools to study a simple family of piecewise isometries of the plane parameterized by an angle. In previous work, we showed the existence of large numbers of periodic points, each surrounded by a ‘periodic island’. We also proved conservativity of the systems as infinite measure-preserving transformations. In experiments it is observed that the periodic islands fill up a large part of the phase space and it has been asked whether the periodic islands form a set of full measure. In this paper we study the periodic islands around an important family of periodic orbits and demonstrate that for all angle parameters that are irrational multiples of π, the islands have asymptotic density in the plane of 3log 2−π2/8≈0.846.

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